Analyzer



Feb. 25, 1958 M. s. SPARKS, JR., ET AL ANALYZER- 2 Sheets-Sheet FiledMay 9, 1955 ANALYZER "'1 I O 53 r 1 PRESSURE REGULATOR 57 55 D ET ECTORFIG. 3

INVENTORS.

M. S. SPARKS, JR. Mv E. REINECKE Feb. 25, 1958 M. s. SPARKS, JR., ET AL2 ANALYZER Filed May 9, 1955 I 2 Sheets-Sheet 2 INVENTORS.

M. E. REINECKE BY I25 I "P A TTORNE VS M. S. SPARKS JR.

ANALYZER Marshall S. Sparks, Jr., and Marvin E. Reinecke, Bartlesville,kla., assignors to Phillips Petroleum Company, a corporation of DelawareApplication May 9, 1955, Serial No. 506,702

8 Claims. (Cl. 250-435) This invention relates to the optical analysisof fluid streams. In another aspect it relates to improved means tosupply a fluid stream to an analyzer at constant temperature andpressure.

Various types of optical analyzers have recently been developed for theanalysis of fluid streams. Certain of these analyzers are based upon theknown fact that some materials absorb electromagnetic radiation at wavelengths characteristic of the material. A vaporized sample of thematerial to be analyzed is directed continuously through a sample cell.A beam of radiation is directed through the cell and the transmittedradiation is measured to determine the concentration of a particularconstituent in the sample stream which absorbs selected wave lengths ofradiation. The accuracy of an analysis of this type depends uponcirculating the sample stream at a constant rate through the opticalcell. Furthermore, the temperature and pressure of the sample streammust be maintained constant because a change in either is likely tochange the radiation absorption properties of the gas.

In accordance with the present invention improved apparatus is providedto supply a gas stream to an analyzer atconstant temperature andpressure. The fluid stream to be analyzed is vaporized, if initiallysupplied as a liquid. The gas is passed through a pressure regulator anda fiow controller to ensure both a constant temperature and a constantflow rate. The optical cell is formed of a block of heat conductivematerial. An elongated passage is formed in the block so that the gassample acquires the temperature of the block before entering the chamberthrough which radiation is transmitted. First and second heatingelements are positioned in the block in spaced relation with one anotherto supply necessary heat to maintain the temperature of the blockconstant at a desired value. These heating elements are energized inresponse to a thermostat which is positioned in closely spacedrelationship with one of the heating elements. The heating elementadjacent the thermostat supplies considerably less heat than does theother element. In this manner the thermostat is energized primarily bythe heat supplied from the smaller element. This results in a moresensitive control than is possible with conventional thermostat meansemploying only a single heating element.

Accordingly, it is an object of this invention to provide an improvedsystem to supply a fluid to an analyzer at a constant rate, temperatureand pressure. 7

Another object is to provide improved apparatus to maintain an elementat a constant temperature. A further object is to provide improvedoptical analysis apparatus.

Other objects, advantages and features of the invention should becomeapparent from the following detailed deatent the temperature of thesample cell constant; and

Figure 7 is a circuit drawing of a second embodiment of the electricalcircuit.

In order to explain the need for and the operation of the presentinvention, reference will be made to a particular application of anultraviolet analyzer employed to control the operation of afractionation column. The fractionation column is provided to separate afluid mixture of butadiene and butene-Z.

Referring now to the drawing in detail and to Figure l in particular,there is shown a fractionation column 10 of any suitable designemploying contacting means such as perforated plates, bubble decks orthe like. The feed mixture to be separated is supplied to column 10through a line 11 at a rate controlled by a conventional rate-offlowcontroller 12 which adjusts a valve 13 in line 11. The feed mixture isseparated within column 10 into a liquid kettle product which iswithdrawn through a line Y 15 and a lower boiling overhead gaseousstream which is withdrawn through a line 16. Heat is supplied to thelower portion of column 10 through a steam line 18 which communicateswith coils 19 disposed in the lower portion of column 10. The rate ofaddition of steam to coil 19 is controlled by a liquid level controller20 which adjusts a valve 21 in line 18 in response to the liquid levelin the lower portion of column 10. The spent steam is removed through aline 22.

The gases which comprise the relatively light compo-v nents of the feedmixture that are not retained in the heavier reboiled bottoms fractionare directed from the upper portion of column 10 through line 16 to acondenser 26 wherein they are partially or completely condensed, as

scription, taken in conjunction with the accompanying control systememploying an analyzer which incorporates Y at r 9 hi ievsnt sas desired,and wherefrom the resulting condensate is directed through a line 28 toa reflux accumulator 29. The

distillate collected in accumulator 29 is discharged through a line 30.A portion of this distillate is directed through a line 31 back into theupper portion of column 10 as reflux. A constant flow rate is maintainedin line 31 by a rate-of-flow controller 32 which adjusts a valve 33 inline 31. The remainder of the distillate removed from accumulator 29 isdirected through an overhead product line 34 at a rate which isproportional to the liquid level in accumulator 29. A valve 35 in line34 is controlled by a liquid level controller 36 which is attached toaccumu-- later 29. In order to maintain the desired operating pressurein column 10, a valve 42 is disposed in line 16 upstream from condenser26. Valve 42 is adjusted by a pressure controller 43 which is actuatedby the pressure in line 16. A line 44 is connected between accumulator29 and line 16 upstream from valve 42. A valve 45 in line 44 is adjustedby a pressure controller 46 in response to the pressure in accumulator29.

The fluid stream supplied to column 10 through iine 11 comprises amixture of butadiene and butene-2. The column is maintained atconditions of temperature and pressure such that the overhead productstream comprises comprises primarily butene- 2. The withdrawal of kettleproduct through line 15 normally is regulated by a ;rate-- of-fiowcontroller 50 which. adjusts a valve 51 in'line 15. A sample stream iswithdrawn continuously from the 6011111111 through n 5. hic em tvni a swith. the.

Patented Feb. 25, 1958 inlet: of pressure regulator The sample stream I,Q Blockilfi is, mounted orija, has

i V V mimicatesdbioughadine'55:withthe inlet 54.A constant flow throughline 55 fist of: 'butadienel-in the sample .st ream-.'1The output signallri l igure6"there.j sislid I e 9740f heat insulating; withdrawnfronieoliimn 10 through line 52 normally is l material. 'The sides andto'p' of. block 70 are covered by a in vapor phase; If this samplestream were a liquid; plates. 98 of heat insulating material. Thisinsulating suitable meansmould'berprovidetl in-gline 52:;togvapgi izfe 7material forms aheatresei voir for the cell assemblyv the mple-The.outlet-:ofipi ssure -ri gu a i r 53com5- First and secondopeningsare formed in block v70 to; receive respective heating elen ents100 and 4101'. A) H] iaed by; third'opening -is formedihfbldzbk, 70"'adjacent heating;

azrate-tofvflow cont'rolleri-fifiwhichadjusts; aivalye -g 57. :element101. -A thermoistatflltnlis positioned inthis Analyzer 54 is adapted todetermine theconcentratioii'i thir'd vop ening of analyzer 54 overridesthe rate-of-fiow'controller SG'tOT electrical circuit'-associated'fwithijheatingelements 1'00 i maintain the' iconcentrationofbutadiene in the sample and 101'a nd'therm0stat 102. Heating elnients100'aridT t stream;at aco'nstant;preselected value. Byi maintainingr. j101- are 'iirgizdahyia soure cfialteriiatingxurrenti1053f theconcentration Dr-pmarme constantfin the .regiorrof-P which has theoutput terminals;th ereoficonnected tore the concentrationof butadienein'th'e-overhe'a'dproductscoupledto one another. Switches 106 an=107engage; stream isalso.maintained within selected limits; 7: 7 respectiveterminals108 and 109 when closed. Switch Radiation: in ;the:ultr'aviolet-;spectrum is provided by a whiclriisielosedzbya:relayjcoil'i 112::beingenergized 7' Analyzer 54: is lus a d s t l y gur -1termiiaalxltlli-iswconnected byf'aqleadjltl to a- 'switehzgslllhydrogen, discharge lamp 6 0. Radiation emittedfronr- S it h 111 engagesa r;termin al 113:;wheii closedi f;Th lamp 160 through-an aperturefilgisdir'ected th'r ughza' it terminal is, connected by'a lead 114 tothq firstiterminal monochromatoi 62 by a collimating lens 63; Theradial-r f:h a i gi lm miloo; Th cond terminal of ;heating'tiontrans'rnittedvthrough 'nionochr omato'r' 62' is' directe dilelernen'tgiltlfl isgconnected bym lead115 407therfirstter f throughapdisc 64 which isirotated by a motor 65. l Thei h f;h ti l m1101;; Th od mi l: of TadiatiOn transmitted thrcughrdlstl 64 is directed ghheatingaelement-101 isLc nne tedby a leadil'l 'ltogswitch-n aSamp'lwellfi p g p i' detector. a pl 'termina1{109:=Switch iterminal'i-108ris;alsoconneetedb y 'Butadiene absorbs:radiaticninrflie vi l p tm byale'ad 1121.10 the: first-terminal of: relayeoil :112: Thesf'circularsectbrsionstfucted of quartzland 'Y respc; mime; mercuryresults in. a circuit being completed 1b proximately 9611mm on x -i n y.p r y 'Thefheatin'gicapaeity tof' elemeri t"l 01 is considerablyofiradiationincidentupon cell 66 increases and-decreases;

line 55' communicates with the inlet of: sample cell 165, a l ad-118' totheifirst'contac t 11910f rthemirorstat; 5- and' ttie gasis vented from"cell 6 hro gh a 1ir' 7- I The'second'icontactf120'ofi'thctmostatr102'islicoim'ected a p x a e y 2 0. Units; U Fsecdndierminalof;;relay:coil*112"is: connected iby ai lea 62eisemployelt0limit-thetransmittedradiation-to"this: ll'2i to switch terminal109.Thermostat=102fCan bci'ini: V i generalregion. Disc6 4 -1'3referablyis formedofjtwo semi-' theifOIm of a mercury; well :arran'gedr sogthat'expansions;

'fivelyi Q n p r t to radiation tweenaterminals lm-and. 120 atapredetermined tempers: of52200 Angstrom. units. Vycor, aglass:containing'ap5 p 1 3 i transparent Wave lengths this region? Thus;i less than :the' heating capacity oflelement 100; Elementthe:absencecf. butadiene insarnple cell 65,- the mag'nitude l lo-l i lipositionediin lo'se' proximityito thermostati ltll; V V p v 7 soE-thaftherm0stat-102 is actuated primarily by theiheatsi periodically atthefrequency at'which disc 64' i's rotated; m iby leme t 101;? This arangeme tgre j inin Afdetectinge'circuii69'i5 onnecteditd C611 66tomeasure a short time lag' between 1135801111301 heat and the's e is-i:if

it e mag fi d 9 this difference in p ld tl'ia'nsij ing*means;- Heatingelement 101 :thus-actuates the the The cell is formed -offa; blockofheat conducting dow 74 and retaining ring 76. Inlet sample linrSS-cboini elongated passage '86 is'd'rille'd in' block 70 to format" whichrcorresptandsa 'continuati'on' of 'port- 85. A seond passage' 87'eiitends. from the inner end of passage 86 Passage 87 is for'med' '87."The outer portion -of passage' '9'lYis blocked by a 'communiationwithfarroutlet port 95' of'flieceih' a While the invention has beendeneifiifeoniiiiiiti5ir mitted radiation;- 'When butadiene is present i-sample -m g priotlitlort'heetgme thatth' th rm t 1d';b

-74 3nd block '70, and aring 81 iS-positio'ned-between win heating.aparcltymf tfieritwpiale ems: i v i Iii'jFi "re T'thmunicateszwithaninlet port 111' block 70. A first; thteligcalrhatmgftingielement f t Figure 6; "isTff fof'thissoit by-drilling a' holeinblock 70and-blocking the outer F f e; ;1 L portion thereof'by a plug 'Athird elongated passage onepftw 1 a demerits" f j z 1 9lisdrilled-iniblock-70-in communication with passage ra e en Yll t rs mes the nee foripvrchase" '7 ing'diffe'renfsized' heatingj'elements:-Elementsi'100and4; V

asaaees with present preferred embodiments it should be evident that theinvention is not limited thereto.

What is claimed is:

1. A sample cell for use in an optical analyzer comprising a block ofheat conductive material having a first radiation transparent passagetherethrough, means forming an elongated inlet fluid passage in saidblock between said first passage and a region exterior of said block,means forming an outlet passage in said block between said first passageand a region exterior of said block, a first heating element in thermalcontact with said block, a second heating element in thermal contactwith said block, said first and second heating elements being spacedfrom one another, the heating capacity of said second element being lessthan the heating capacity of said first element, a thermostat in thermalcontact with said block adjacent said second element, and means toenergize said first and second elements responsive to said thermostat.

2. The combination in accordince with claim 1 further comprising a massof heat insulating material enclosing said block. v

3. A sample cell for use in an optical analyzer comprising a block ofheat conductive material having a first radiation transparent passagetherethrough, means forming an elongated inlet fluid passage in saidblock between said first passage and a region exterior of said block,means forming an outlet passage in said block between said first passageand a region exterior of said block, a first electrical heating elementin said block, a second electrical heating element in said block, saidfirst and second heating elements being spaced from one another, theheating capacity of said second element being less than the heatingcapacity of said first element, a thermostat in thermal contact withsaid block adjacent said second element, a current source, and circuitmeans to energize said first and second elements from said currentsource responsive to said thermostat.

4. A sample cell for use in an optical analyzer comprising a block ofheat conductive material having a first passage therethrough, aradiation transparent window positioned in each end of said firstpassage, a mass of heat insulating material enclosing said block, meansforming an elongated inlet fluid passage in said block between saidfirst passage and a region exterior of said block, means forming anoutlet passage in said block between said first passage and a regionexterior of said block, a first electrical heating element in saidblock, a second electrical heating element in said block, said first andsecond heating elements being spaced from one another, the heatingcapacity of said second element being less than the heating capacity ofsaid first element, a thermostat in thermal contact with said blockadjacent said second element, a current source, a relay to control theapplication of current from said source to said heating elements, andcircuit 55 in said first and second heating elements are connected inseries relationship with said current source through said relay, theresistance of said second element being less than the resistance of saidfirst element.

5 6. The combination in accordance with claim 4 wherein said first andsecond heating elements are connected in series relationship with saidcurrent source through said relay, the resistance of said second elementbeing substantially equal to the resistance of said first element, and

a resistor connected in shunt with said second element.

7. Apparatus for use with optical analyzers comprising a conduit tosupply a fluid to be analyzed, a rate-of-flow controller in saidconduit, a pressure regulator in said conduit, a block of heatconductive material having a first radiation transparent passagetherethrough, means forming an elongated inlet passage in said blockbetween said first passage and a region exterior of said block incommunication with the outlet of said conduit, means forming an outletpassage in said block between said first passage and a region exteriorof said block, a first heating element in thermal contact with saidblock, a second heating element in thermal contact with said block, saidfirst and second heating elements being spaced from one another, theheating capacity of said second element being less than the heatingcapacity of said first element, a

thermostat in thermal contact with said block adjacent said secondelement, and means to energize said first and second elements responsiveto said thermostat.

8. An analyzer comprising a conduit to supply a fluid to be analyzed, arate-of-flow controller in said conduit,

a pressure regulator in said conduit, a block of heat conductivematerial having a first radiation transparent passage therethrough,means forming an elongated inlet passage in said block between saidfirst passage and a region exterior of said block in communication withthe outlet end of said conduit, means forming an outlet passage in saidblock between said first passage and a region exterior of said block, afirst heating element in thermal contact with said block, a secondheating element in thermal contact with said block, said first andsecond heating elements being spaced from one another, the heatingcapacity of said second element being less than the heating capacity ofsaid first element, a thermostat in thermal contact with said blockadjacent said second element, and means to energize said first andsecond elements responsive to said thermostat.

References Cited in the file of this patent UNITED STATES PATENTS1,519,555 Ruben Dec. 16, 1924 2,692,820 Alway et al. Oct. 26, 1954 OTHERREFERENCES Construction of a Dual Beam Heated Infrared Cell, by John T.Neu, from Journal of the Optical Society of America, vol. 43, No. 6,June 1953, pages 520, 521.

